diff --git a/vrtManager/instance.py b/vrtManager/instance.py
index f783dd78..79729784 100644
--- a/vrtManager/instance.py
+++ b/vrtManager/instance.py
@@ -248,10 +248,11 @@ class wvmInstances(wvmConnect):
     @staticmethod
     def moved_disks(xml, copies):
         """xml with each copied disk's source at its path here; a disk is
-        found by its target and its source path before the copy."""
+        found by its source path before the copy, as the next start's
+        definition may name it with another target (a changed bus)."""
         tree = etree.fromstring(xml)
         sources = [(source, copy["dest"]) for copy in copies for source in tree.xpath(
-            "devices/disk[target/@dev=$target]/source[@file=$path]", target=copy["target"], path=copy["path"])]
+            "devices/disk/source[@file=$path]", path=copy["path"])]
         for source, dest in sources:
             source.set("file", dest)
         return etree.tostring(tree, encoding="unicode")
@@ -367,9 +368,12 @@ class wvmInstances(wvmConnect):
                     "%(target)s (%(path)s): pool %(pool)s of the destination host already has a file %(file)s"),
                     **disk, pool=name, file=file))
                 continue
-            if any(copy["dest"] == f"{directory}/{file}" for copy in copies):
+            # one file, one copy: the definitions name a disk's copy by its path
+            other = next((copy for copy in copies if copy["dest"] == f"{directory}/{file}"
+                          or copy["path"] == row["path"]), None)
+            if other is not None:
                 problems.append(util.message(gettext_noop("%(target)s (%(path)s): another disk is copied to %(dest)s"),
-                                             **disk, dest=f"{directory}/{file}"))
+                                             **disk, dest=other["dest"]))
                 continue
             copies.append({"target": row["target"], "path": row["path"], "dest": f"{directory}/{file}",
                            "pool": pool})
diff --git a/vrtManager/tests/test_disk_copy_migration.py b/vrtManager/tests/test_disk_copy_migration.py
index dff4be43..12ded116 100644
--- a/vrtManager/tests/test_disk_copy_migration.py
+++ b/vrtManager/tests/test_disk_copy_migration.py
@@ -231,6 +231,13 @@ class DiskCopyTestCase(unittest.TestCase):
         self.assertIn(f'<source file="{FAST}/vm.qcow2"/><target dev="vda"/>', dest_xml)
         self.assertIn('<source file="/srv/slow/vm.qcow2"/><target dev="vdb"/>', dest_xml)
 
+    def test_the_next_start_names_the_copy_under_another_target_too(self):
+        """A bus change waiting for the next start renames the disk there."""
+        source = Source(1, domain(disk(f"{IMAGES}/vm.qcow2")), inactive=domain(disk(f"{IMAGES}/vm.qcow2", "sda")))
+        migrate(destination(Pool("default", IMAGES), Pool("fast", FAST)), source, {"vda": "fast"})
+        params = source.instance.migrate3.call_args.args[1]
+        self.assertIn(f'<source file="{FAST}/vm.qcow2"/><target dev="sda"/>', params[libvirt.VIR_MIGRATE_PARAM_PERSIST_XML])
+
     def test_a_disk_only_the_next_start_has_must_be_shared_too(self):
         """It is neither copied nor moved: a file of its name on the
         destination would be another VM's, used at the next start."""
@@ -241,6 +248,14 @@ class DiskCopyTestCase(unittest.TestCase):
             migrate(destination(Pool("default", IMAGES)), source, {"vda": "default"})
         source.instance.migrate3.assert_not_called()
 
+    def test_one_file_two_disks_use_is_copied_once(self):
+        xml = domain(disk(f"{IMAGES}/data.raw", "vda", fmt="raw"), disk(f"{IMAGES}/data.raw", "vdb", fmt="raw"))
+        source = Source(1, xml, pools=(IMAGES,))
+        dest = destination(Pool("fast", FAST), Pool("slow", "/srv/slow"))
+        with self.assertRaisesRegex(util.OperationError, f"vdb \\({IMAGES}/data.raw\\): another disk is copied to {FAST}/data.raw"):
+            migrate(dest, source, {"vda": "fast", "vdb": "slow"})
+        source.instance.migrate3.assert_not_called()
+
     def test_two_copies_never_go_to_one_file(self):
         source = Source(1, domain(disk(f"{IMAGES}/vm.qcow2"), disk(f"{FAST}/vm.qcow2", "vdb")), pools=(IMAGES, FAST))
         with self.assertRaisesRegex(util.OperationError, "vdb .*another disk is copied to /srv/slow/vm.qcow2"):